1. Field of the Invention
The invention relates to a diagnostic device for at least one pneumatic valve actuator arrangement, comprising a pressure sensor, a volumetric flow sensor, a control means for the production of control signals for the valve actuator arrangement and position sensors for finding the position of at least one moving actuator member.
2. Description of the Related Art
Such diagnostic devices are for example disclosed in the German patent publications 19628221 C2 and 10052664 A1 and serve more particularly for process monitoring. In the case of the known devices stored reference characteristics for pressure, as for example at an actuator and/or for the volumetric flow rate of the pneumatic medium are compared with currently measured pressure characteristics and volumetric flow rate characteristics, departures from predetermined tolerances leading to diagnostic warnings. The known devices are merely suitable for determining the position of the fault, i.e. at which valve or which actuator or which valve actuator arrangement is failing in its function. The precise type of fault in function may however not be found using the known devices.